Various means have been used to relax and soothe a person using vibrations in the acoustic range (generally 20 to 20,000 Hertz). For example, calming music is frequently delivered via conventional speakers or, headphones. Herein, vibration of the air or of a solid medium in the frequency range of 20 to 20,000 Hz will be generally called “sound vibration” or acoustic vibration.” Vibration in that frequency range that is exclusively of the air and perceived by the ears will be called “audible vibration” or “audible sound.”
Sometimes the delivery of calming music is combined with a pleasant visual display, as with a visor or helmet that includes both headphones and a device for displaying images to the eyes, for example colored lights that change in accord with changes in the music delivered by the headphones.
For example, Douglas et al. disclose in U.S. Pat. No. 6,702,767 an elaborate multi-sensory stimulation booth capable of presenting a person with colored lights or images, music or other sounds, aromas, and cool or warm breezes. The system is stated as producing either relaxation or entertainment, and is asserted as providing unusual perceptions, such as a feeling of floating.
Music or sound may be combined with a massage-like effect. The patents of Soza (U.S. Pat. No. 6,104,820) and Komatsu (U.S. Pat. No. 6,369,312), for example, disclose body relaxation systems that combine music with vibrations delivered to other parts of the body. In the case of Soza, music delivered to the ears by headphones is emphatically augmented by “massage” of muscle groups. The same electrical signals that are converted to sound by the headphones are also applied directly to the skin by electrodes. Komatsu discloses a chair in which music is played by speakers close to the ears, while transducers in the back and seat of the chair massage portions of the body with lower frequency vibrations (16 to 150 Hertz) that are related to the heard music in some manner, such as duration.
Conventional systems that combine vibration of parts of the body with audible sounds delivered to the ears by headphones or speakers have several shortcomings. Most obviously, headphones or helmets can interfere with relaxation and only deliver a small amount of vibro-acoustic energy. Speakers, even if built into a chair such that they are close to a person's head, by their nature put sound into the ambient air. The audible sound may be bothersome to other nearby persons or interfere with the relaxation therapy of other persons.
Less obviously, certain types of music or sounds are thought of as being relaxing, but individual persons have individual responses to any music or sounds. For example, some people are soothed by sounds of thunder and pouring rain; others find such sounds very distressing. Any audible sounds delivered by means of a person's hearing are filtered through that person's culture, experiences, and aesthetic taste, among many factors.
Speakers or headphones can transmit very little energy into a person for two reasons. Firstly, strong sounds damage the ears, so there is a strict upper limit to the amplitude of audible vibrations that can be delivered safely. Secondly, speakers, including those of headphones, vibrate the ambient air to transmit sound energy in an expanding sphere of sound. Not much energy is actually received by any given spot on the human body. The ears perceive the sound because they are exquisitely sensitive to vibrations in the acoustic range. Only the very loudest audible sounds are perceived by the rest of the body, but such loud sounds are unsuitable for use therapeutically because they are ear-damaging.
Devices that directly vibrate portions of the body other than the ears deliver approximately 25 times the vibration energy to a body that speakers or headphones do, for a given input energy. Direct vibration of the body also allows greater energy to be imparted without risk of damage to the ears. However, direct vibration of the body, as taught by Soza or Komatsu, for example, is typically perceived as a simple “buzzing” sensation that is relaxing by its anesthetic effect on the muscles.
Researchers and therapists have believed for some time that sensory stimulation affects a person more quickly and deeply if the stimulation targets the halves of the brain separately. By simultaneously presenting each hemisphere of the brain with a therapy tailored to that hemisphere's functions and abilities, a well-designed therapy would proceed very quickly and with potential synergy between the hemispheres.
Attempts have been made to provide bi-lateral stimulation of the brain hemispheres by use of specialized headphones or visors. As discussed above, the amount of acoustic energy that can be transmitted by headphones is very limited. Another weakness of administering bi-lateral acoustic sound through headphones is that the sound travels to the brain via the acoustic nerve only. The sound is evaluated according to taste and experience, as discussed above, with certain sounds possibly having unintended significance due to positive or negative conditioning.
An attempt has been made (McNew, U.S. Pat. No. 6,544,165) to stimulate the halves of a person's body with vibrations from speakers attached in pairs to a body support. The speakers are shown attached to the bottom of a body support, with small holes to help the sound penetrate to the supported body. The speakers are surrounded by attenuating housings to prevent sound from being emitted into the ambient air.
This apparatus bypasses the problems of using the ears as the object of the sensory stimulation, but maintains the weakness of trying to stimulate the skin with audible sound instead of vibration transmitted by a solid medium.
Also, separation of the vibro-acoustic vibrations to separate sides of the body is not complete, even with “attenuating housings.” Vibrations will be transmitted throughout the support, which is disclosed as being of wood or metal, among other materials. This mixing of the vibrations severely undercuts the aim of providing different stimulations to the two sides of the body and, hence, the brain.
There is a need for an apparatus that can stimulate the two sides of the human body with different and discrete vibrations in the acoustic frequency range.
There is a need for comfortable article's of furniture of various types for delivering bi-lateral acoustic stimulation to the brain and brainstem in order to promote relaxation, stress relief, or sleep.